A bastion is a protruding section of a fortified area that allows for defensive fire in several directions. It can also be simply a stronghold or fortified place. Over time the word has come to include metaphorical bastions or places that protect certain ideas or activities. This last definition is used often with the modifier last.
The adjective form is bastioned.
According to Google’s Ngram Viewer, bastion is enjoying the same frequency now as it did in 1880. The peak of popularity was around 1860 and the least usage was around 1930.
Examples
Once a strong bastion of Maoists and Janashakti, this interior village in Yellareddypet mandal abutting the dense forests is now on the path of development. [News Hub]
As the last bastion of the multicultural caliphate in Spain, Granada has always occupied a romantic place in the Spanish cultural consciousness. [UCSD Guardian]
In almost all seats, which had traditionally been Congress bastions – the vote share for the party has reduced significantly alongside a parallel meteoric increase in AAP’s vote share. [Indian Express]
The bastioned stone walls, built by Dutch settlers in the 17th and 18th centuries, seem to belong to a faraway era when there was a threat of bloody conflict, not in what is now a quiet bay in southwest Sri Lanka. [Financial Times]
The royal court, bastioned by old soldiers and members of hereditary aristocracy, surrounds the monarchy with a self-aggrandising, protective and defensive oligarchy which benefits none but itself. [Huffington Post]